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x86, cpufeature: Add cpufeature flag for SMEP

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Add support for newly documented SMEP (Supervisor Mode Execution Protection) CPU
feature flag.

SMEP prevents the CPU in kernel-mode to jump to an executable page
that has the user flag set in the PTE.  This prevents the kernel from
executing user-space code accidentally or maliciously, so it for
example prevents kernel exploits from jumping to specially prepared
user-mode shell code.

[ hpa: added better description by Ingo Molnar ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
LKML-Reference: <1305683069-25394-2-git-send-email-fenghua.yu@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Fenghua Yu 2011-05-17 18:44:26 -07:00 committed by H. Peter Anvin
parent 724a92ee45
commit d0281a257f
1 changed files with 1 additions and 0 deletions
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arch/x86/include/asm/cpufeature.h
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@ -195,6 +195,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */
#define X86_FEATURE_FSGSBASE (9*32+ 0) /* {RD/WR}{FS/GS}BASE instructions*/
#define X86_FEATURE_SMEP (9*32+ 7) /* Supervisor Mode Execution Protection */
#define X86_FEATURE_ERMS (9*32+ 9) /* Enhanced REP MOVSB/STOSB */
#if defined(__KERNEL__) && !defined(__ASSEMBLY__)